In the current process of miniaturizing semiconductor devices, low-k dielectric materials are desired as the inter-metal and/or inter-layer dielectric between conductive interconnects in order to reduce the resistive-capacitive (RC) delay in signal propagation due to capacitive effects. As such, the lower the dielectric layer constant of the dielectric, the lower the parasitic capacitance of adjacent conductive lines and the lower the RC delay of the integrated circuit (IC).
A low-k dielectric layer may be formed by initially forming a precursor film. This precursor film may have two components such as a matrix material and a porogen material formed within the matrix material. Once the precursor film has been formed and solidified in the area in which the low-k dielectric material is desired, the porogen may be removed from the precursor film, thereby forming “pores” which lower the dielectric constant of the precursor film and form the low-k dielectric material.
However, the porogens currently in use, such as 1-isopropyl-1-4-methyl-1,3-cyclohexadiene (ATRP) or bicyclo(2.2.1)-hepta-2,5diene (BCHD), generally have poor flow characteristics as they are being used to form the low-k dielectric layer. In particular, these porogens may diffuse momentum ineffectively, causing variations in the cross-section of the flow as the porogens are being transported and causing an uneven distribution throughout the low-k-dielectric layer. Additionally, the use of these porogens may also form a low-k material that adheres poorly to underlying layers, and may also need higher energies in order to be incorporated within the precursor film and cross link within the precursor film.
Corresponding numerals and symbols in the different figures generally refer to corresponding parts unless otherwise indicated. The figures are drawn to clearly illustrate the relevant aspects of the embodiments and are not necessarily drawn to scale.